In a maintenance method of an inkjet printer comprising an air discharge device which discharges air accumulated in ink supply paths with pressurized air and an ink vacuum device which vacuums ink from an inkjet head, the pressurized air is in a high pressure mode when the air discharge device is used. The pressurized air is in a low pressure mode when the ink vacuum device is used. The driving time and the rotational speed of a drive motor which drives an air pump are controlled according to the capability and the ambient temperature of the air pump which generates the pressurized air.